It has been recently demonstrated that dihydronepetalactone exhibits insect repellency (see, for example, U.S. Ser. No. 05/112,166). Dihydronepetalactone can be obtained from the essential oil of the catmint plant, Nepeta cataria. Essential oil from N. cataria, herein referred to as catmint oil, has been obtained by various isolation processes, including steam distillation, organic solvent extraction, microwave-assisted organic solvent extraction, supercritical fluid extraction, mechanical extraction and enfleurage (initial cold extraction into fats followed by organic solvent extraction). Steam distillation [such as described by Regnier, F. E. et al, Phytochemistry (1967) 6:1281-1289] is the most economically viable method for obtaining catmint oil.
Yields of catmint oil obtained using standard distillation techniques are likely insufficient, however, for commercial production of the insect repellent dihydronepetalactone as derived from catmint oil. A need thus remains for improved techniques for the recovery of catmint oil from catmint plants.